Flip audio quality is pretty amazing, considering how small the microphone has to be to fit into the Flip's body.  But sometimes it may not be good enough.  How can you match up Flip video with audio recorded with other equipment?

Let's say you're recording yourself singing a song with your guitar. Ordinarily, you do this with a decent mic or two and some recording gear, but you would like to catch the video, too.

Your Flip records quality video, but doesn't give you the kind of audio quality you would like for this use. Also, you would like to do a little mixing and sweetening with the sound, adjusting levels, adding some some reverb, etc.

The next possibility is to set your Flip up on a tripod and shoot while you use your usual sound recording gear to capture and mix the sound. But there remains the problem of bringing the two together, replacing the Flip's sound with the recorded audio track, and making sure the sound and video are in synch.

Here's a trick:

1. Start the camera and the sound recorder.
2. Clap your hands three times.
3. Record your music.
4. Clap three times.

Bring the audio and video together in a video editing program that shows the audio as waveforms. The claps produce sharp transients in the waveforms in both the Flip audio track and your separately recorded track. All you need to do then is to line up those spikes. Generally, with digital audio and video, there shouldn't be enough speed variation to be of concern. However, if you're using analog audio gear, it might be a problem.

If you're using a video editing program like Sony Vegas (Movie Studio or Pro), you can account for minor variations in speed. So, if you line up the claps at the beginning of your video and the claps at the end of the video don't quite match up, you can tweak the video speed for an absolutely perfect match.